<html>
<head>
  <script type="text/javascript">
window.onload = function() {
    var ctx = document.getElementById("c1").getContext("2d");

    ctx.lineWidth = 5;

    ctx.setLineDash([ 5, 10 ]);  // 5 on, 10 off
    ctx.moveTo(50, 50);
    ctx.lineTo(250, 50);
    ctx.stroke();
    ctx.beginPath();

    ctx.lineDashOffset = 5;
    ctx.moveTo(50, 100);
    ctx.lineTo(250, 100);
    ctx.stroke();
    ctx.beginPath();

    ctx.lineDashOffset = 5;
    ctx.setLineDash([ 5 ]);  // 5 on, 5 off
    ctx.moveTo(50, 150);
    ctx.lineTo(250, 150);
    ctx.stroke();
    ctx.beginPath();

}
  </script>
</head>
<body style="padding: 0px; margin: 0px;">
  <div><canvas id="c1" width="300" height="300"></canvas></div>
</body>
</html>
